[PATCH net-next V2 00/11] net/mlx5e: Add support for devmem and io_uring TCP zero-copy

Tariq Toukan
2025-05-22T21:42:25Z

This series from the team adds support for zerocopy rx TCP with devmem
and io_uring for ConnectX7 NICs and above. For performance reasons and
simplicity HW-GRO will also be turned on when header-data split mode is
on.

Find more details below.

Regards,
Tariq

Performance
===========

Test setup:

* CPU: Intel(R) Xeon(R) Platinum 8380 CPU @ 2.30GHz (single NUMA)
* NIC: ConnectX7
* Benchmarking tool: kperf [1]
* Single TCP flow
* Test duration: 60s

With application thread and interrupts pinned to the *same* core:

|------+-----------+----------|
| MTU | epoll | io_uring |
|------+-----------+----------|
| 1500 | 61.6 Gbps | 114 Gbps |
| 4096 | 69.3 Gbps | 151 Gbps |
| 9000 | 67.8 Gbps | 187 Gbps |
|------+-----------+----------|

The CPU usage for io_uring is 95%.

Reproduction steps for io_uring:

server --no-daemon -a 2001:db8::1 --no-memcmp --iou --iou_sendzc \
--iou_zcrx --iou_dev_name eth2 --iou_zcrx_queue_id 2

server --no-daemon -a 2001:db8::2 --no-memcmp --iou --iou_sendzc

client --src 2001:db8::2 --dst 2001:db8::1 \
--msg-zerocopy -t 60 --cpu-min=2 --cpu-max=2

Patch overview:
================

First, a netmem API for skb_can_coalesce is added to the core to be able
to do skb fragment coalescing on netmems.

The next patches introduce some cleanups in the internal SHAMPO code and
improvements to hw gro capability checks in FW.

A separate page_pool is introduced for headers. Ethtool stats are added
as well.

Then the driver is converted to use the netmem API and to allow support
for unreadable netmem page pool.

The queue management ops are implemented.

Finally, the tcp-data-split ring parameter is exposed.

Changelog
=========

Changes from v1 [0]:
- Added support for skb_can_coalesce_netmem().
- Avoid netmem_to_page() casts in the driver.
- Fixed code to abide 80 char limit with some exceptions to avoid
code churn.

References
==========

[0] v1: https://lore.kernel.org/all/20250116215530.158886-1-saeed@kernel.org/
[1] kperf: git://git.kernel.dk/kperf.git

Dragos Tatulea (1):
net: Add skb_can_coalesce for netmem

Saeed Mahameed (10):
net: Kconfig NET_DEVMEM selects GENERIC_ALLOCATOR
net/mlx5e: SHAMPO: Reorganize mlx5_rq_shampo_alloc
net/mlx5e: SHAMPO: Remove redundant params
net/mlx5e: SHAMPO: Improve hw gro capability checking
net/mlx5e: SHAMPO: Separate pool for headers
net/mlx5e: SHAMPO: Headers page pool stats
net/mlx5e: Convert over to netmem
net/mlx5e: Add support for UNREADABLE netmem page pools
net/mlx5e: Implement queue mgmt ops and single channel swap
net/mlx5e: Support ethtool tcp-data-split settings

drivers/net/ethernet/mellanox/mlx5/core/en.h | 11 +-
.../ethernet/mellanox/mlx5/core/en/params.c | 36 ++-
.../ethernet/mellanox/mlx5/core/en_ethtool.c | 50 ++++
.../net/ethernet/mellanox/mlx5/core/en_main.c | 281 +++++++++++++-----
.../net/ethernet/mellanox/mlx5/core/en_rx.c | 136 +++++----
.../ethernet/mellanox/mlx5/core/en_stats.c | 53 ++++
.../ethernet/mellanox/mlx5/core/en_stats.h | 24 ++
include/linux/skbuff.h | 12 +
net/Kconfig | 2 +-
9 files changed, 445 insertions(+), 160 deletions(-)

base-commit: 33e1b1b3991ba8c0d02b2324a582e084272205d6
--
2.31.1